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De-flapping how-to guide (long)

 
Old 01-25-2009, 01:47 PM
  #1  
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Default De-flapping how-to guide (long)

Since I decided to check and re-install my spark plugs the other day, I decided to (finally) de-flap the car as well. Might as well - you have to remove the top air box to get to the spark plugs anyway. Thanks to Bob W. and Mickf29 for their previous instructions and inspiration. This write-up is intended to be a more comprehensive DIY guide so you'll know exactly how to de-flap if you choose to do so. Why you might want to de-flap is another subject that has been discussed here at length before.

This procedure took me about 1 hour including taking pictures.

<a href="http://cid-783172b85ef70f5e.skydrive.live.com/self.aspx/.Public/De-Flap%20How%20To%20Guide.mht">Link to downloadable document</a>

Here are the tools and parts you'll need:
* Gloves to wrestle the bottom air box out
* 6" or longer T30 Torx driver for headlamp removal
* Flat blade screwdriver for hose clamp
* #2 Philips screwdriver
* Box cutter for cutting tape
* Pliers for removing the air box clip
* Side cutters for cutting the flap vacuum hose
* Small flash light (I also used a shop light to illuminate the engine compartment)
* Electrician's tape for taping down a wiring harness
* Two small zip ties
* One #8-32 X 1" machine screw for plugging the vacuum line

Also useful: compressed air and a vacuum for cleaning out dirt and debris from the filters and air box.

<img src="http://pictureposter.audiworld.com/112310/img_2302a.jpg">

Start by removing the rear engine carbon fiber cover. The air guide hose you see coming out from under the left side of carbon fiber cover will need some room to flex. I find the best way to remove this is to grasp the back part of the cover and pull straight up.

<img src="http://pictureposter.audiworld.com/112310/img_2269a.jpg">

Next, remove the front/top air duct. Remove the two Philips-head screws (red arrows), then lift the left side (green arrow) up out of the air box socket:

<img src="http://pictureposter.audiworld.com/112310/img_2271a.jpg">

This is what it looks like when you pull the air duct of the air box socket. You can then slide the front of the air duct out from underneath the mounting point where you just removed the two screws.

<img src="http://pictureposter.audiworld.com/112310/img_2272a.jpg">

This is a good time to inspect and clean the pre-filter. Remove it from the "socket" end of the air duct and blow it out with compressed air, and then reinstall. It should fit flush with the end of the air duct.

<img src="http://pictureposter.audiworld.com/112310/img_2273a.jpg">

Next, loosen the hose clamp on the air guide hose (red arrow) and pull the air guide hose off the Mass Air Flow (MAF) sensor housing. Disconnect the electrical harness connector at the MAF sensor (green arrow).

<img src="http://pictureposter.audiworld.com/112310/img_2270a.jpg">

To remove the electrical harness connector, push the connector in while at the same time using your finger to pull down (away from the MAF sensor) the release tab (red arrow). You should hear a "click" and then you'll be able to pull the connector off.

<img src="http://pictureposter.audiworld.com/112310/img_2275a.jpg">

Next, remove the hose that is clamped on top of the air box - just pull it straight up.

<img src="http://pictureposter.audiworld.com/112310/img_2277a.jpg">

Pull the hose on the right side of the air box (between the air box and engine) out of its clamp/guide (red arrows). Remove the Secondary Air Injection hose by squeezing the two ribbed sections of the connector together (green arrows). You just have to press and wiggle the connector a little and it will pop off easily; no pulling needed.

<img src="http://pictureposter.audiworld.com/112310/img_2278a.jpg">

Now it's time to unscrew the two screws holding the top cover of the air box to the bottom (red arrows). You don't need to remove the screws, just loosen them until the top comes free. The top cover is essentially hinged (but not connected) on the engine side, so tilt the top cover towards the engine and then pull up and out.

<img src="http://pictureposter.audiworld.com/112310/img_2299a.jpg">

Here is the inside of the top cover. You can see the MAF assembly (red arrow) in the air guide. Note the hinge fingers (green arrows) on the cover; these fit underneath tabs on the bottom portion of the air box to form a hinge.

<img src="http://pictureposter.audiworld.com/112310/img_2280a.jpg">

Here's a view of opened air box. Remove the air filter.

<img src="http://pictureposter.audiworld.com/112310/img_2281a.jpg">

You'll probably find some sand, dirt, etc. in the bottom of the air box, so vacuum it out now. You can see the horn/flap assembly here (red arrow) just peeking into the air box - most of the assembly is on the outside underneath the headlamp assembly (with the yellow lightning bolt sticker). Next steps are to remove the air box clip (green arrow) and the wiring harness that is taped to two guides (blue arrows) attached to the air box.

<img src="http://pictureposter.audiworld.com/112310/img_2284a.jpg">

This took me a few minutes to figure out. To remove the clip, pull the center insert pin out - I used pliers to start the process. This center insert pin pushes against an anchor that fits inside a hole on the inside of the fender - once the center insert pin is out gently pull the clip out away from the fender. The clip has two pieces that sandwich the tab on the air box. Mine pulled apart at this point so I set them aside. Yours may stay together so you may want to leave them on the air box.

<img src="http://pictureposter.audiworld.com/112310/img_2282a.jpg">

<img src="http://pictureposter.audiworld.com/112310/img_2283a.jpg">

Now, un-wrap the tape that attaches the wiring harness to the metal wiring guides. There are two wraps per guide. This is what it looks like when you're done:

<img src="http://pictureposter.audiworld.com/112310/img_2288a.jpg">

One more step left to go before removing the air box bottom - you'll want to pull the passenger-side headlamp assembly out ½ - 1". You will need the 6" (or longer) T30 Torx driver for this step. Loosen (don't remove!) the two Torx bolts indicated by the red arrows. The one on the right is clearly visible, but the one on the left is accessed via a hole in the body and is almost 6" down. You'll have to locate this one by feel, but it is possible to peer down the hole with a small flashlight to give you an idea where it is.

Remove the center Torx bolt (green arrow) and pull the headlight assembly forward about ½ - 1".

<img src="http://pictureposter.audiworld.com/112310/img_2285a.jpg">

This is the hard part. You'll need to lift up on the lower air box to remove the two standoffs from their grommets (red arrows) and then pull it out while twisting the back of the assembly up towards the front of the car. You need to do this because the horn/flap assembly is still underneath the headlamp assembly.

As the air box starts to come free, you'll see the vacuum valve assembly on the side of the horn/flap assembly. Obviously it's still attached to the vacuum hose, so you'll either need to pull the hose off the valve or use a pair of side-cutters to cut it (green arrow). I didn't have enough room or leverage to do the former so I decided to cut the hose (no going back now!). You may have better luck pulling the hose off than I did.

I also found that if you tuck the Secondary Air Injection hose (blue arrow) under the headlamp and out of the way, it freed up enough room to allow air box to come free. I recommend using a pair of mechanic's gloves for this step to avoid cuts and scratches.

<img src="http://pictureposter.audiworld.com/112310/img_2289a.jpg">

Here is the lower air box assembly. You can see the two standoffs on the right (red arrows). Curiously one is plastic, the other rubber. The horn/flap assembly and vacuum valve is at the bottom (green arrow). It's held on by two Philips-head screws. Remove the screws to remove the horn/flap assembly. Based on the MAF readings that Bob W. and others have done, I decided to remove the whole assembly. If you choose to remove only the flap and leave the horn, you can snap the flap out. Leaving the horn off makes installation of the air box much easier.

<img src="http://pictureposter.audiworld.com/112310/img_2293a.jpg">

Next, plug the vacuum line that was cut (or pulled off). I used a #8-32 X 1" machine screw to plug the line - it' the perfect size (in fact you need to screw it into the hose) and then I used two small zip ties pulled tight to seal it off. There should be a hose clip already on the vacuum line (red arrow) you can use to clip it to another nearby vacuum line.

<img src="http://pictureposter.audiworld.com/112310/img_2291a.jpg">

Now it's time to re-install everything. First, reinsert the bottom air box into the large grommets (shown above). Without the horn assembly, this air box should pretty much plug straight in.

<img src="http://pictureposter.audiworld.com/112310/img_2296a.jpg">

Install the air box clip. It sandwiches the ring on the air box (see above picture) and plugs into the hole in the fender (also seen above). Push the center insert pin to expand the anchor inside the hole. Re-tape the wiring harness onto the two metal guides using your favorite electrician's tape.

<img src="http://pictureposter.audiworld.com/112310/img_2298a.jpg">

Push in the headlamp assembly, and tighten down the two Torx bolts on either side while holding the headlamp assembly in. Reinstall the center Torx bolt.

Place the air filter into the lower air box. Make sure it seats properly at the edges.

Install the top air box assembly. Lead with the hinge fingers and make sure they hook under the tabs on the lower air box. Once the hinges are in place push the left side of the top air box down and screw in the two screws (red arrows below).

Reinstall the Secondary Air Injection hose (green arrow) - just plug it in until it clicks. Replace the hose on the right side of the air box into its guide (blue arrow).

Reinstall air guide hose onto MAF air guide assembly with hose clamp (yellow arrow). Clip hose back onto the flat standoff (white arrow). Reinstall MAF sensor harness (purple arrow).

<img src="http://pictureposter.audiworld.com/112310/img_2299b.jpg">

Finally, reinstall the air duct. Slip the front edge under the hood gasket in the front and then pop the back/left part of the air duct back into the hole on top of the air box. It just snaps in place. Align the screw holes on the front of the air duct and reinstall the screws (red arrow). Reinstall the rear engine carbon fiber cover by pushing it down into the thre ball sockets. That's it, you're done!

<img src="http://pictureposter.audiworld.com/112310/img_2300a.jpg">
ski35off is offline  
Old 01-25-2009, 01:59 PM
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Default well done. the only comment I would make...

...is that you don't have to unwrap that wiring harness. You can leave the metal clips attached....they'll just pull out from the attachment points, and then pop back into place when putting everything back together. Obviously, you'll want to grasp the metal clip and harness together and pull it out gently.
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Old 01-25-2009, 02:14 PM
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Default

Ah, I couldn't tell if the clips would break, so I opted to un-wrap
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Old 01-25-2009, 02:23 PM
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Default Excellent write-up. Thanks for taking the time. I opted to leave my flap in..

I initially was worried about "sticking" problem. But once I figured out how to easily test its operation with Vag-com, and mine appeared to be working properly, I left it in. The same operation test can be used for the intake manifold flaps. Pretty handy tool if you ask me.
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Old 01-25-2009, 02:26 PM
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Default great write up...thnx

this will be helpful for changing the air filter...

one suggestion to add, clean the MAF when you have access using CRC AFM cleaner...

Bob's air flow readings you refer to? does the flap limit flow/HP during wide open throttle?<ul><li><a href="http://www.crcindustries.com/auto/content/products_ss.aspx?ID=90">http://www.crcindustries.com/auto/content/products_ss.aspx?ID=90</a</li></ul>
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Old 01-25-2009, 03:03 PM
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Default I took the horn with the flap apart and took the flap out...

and then hooked the vacuum line up again.
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Old 01-25-2009, 05:38 PM
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Default Thank you!

I has been wondering how to take the MAF sensor connector without breaking it in the process. This write up will definite help those who want to change the air filter without struggling with space. Thanks again ski35off.
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Old 01-25-2009, 05:56 PM
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Default Nice job

I followed the instructions that had been posted previously and was actually able to do it without removing the headlight. It wasn't easy to do, but it can be done.
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Old 01-25-2009, 06:37 PM
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This is the sort of thing everyone appreciates on forums, thanks.
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Old 01-25-2009, 07:05 PM
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Default i'll 2nd that...first time I did it w/o touching the headlight.

however, when I reinstalled the horn for my horn vs. no-horn MAF tests, I loosened the headlight housing so I could pull it back slightly, which helps a lot.
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